Conformational effects on complex formation in polymeric systems and matrix polymerization

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Abstract
Kabanov et al. reported that a complex could be formed between poly-L-lysine (I) and poly(acrylic acid) (II) which stabilizes the α-helix of I. In order to confirm this important result, the complex formation between I and various dicarboxylic acids of different chain lengths has been examined. Glutaric acid, whose extended chain length coincides with the distance between the adjacent amino groups of the I chain in the α-helix form was found to stabilize the α-helix. The structures of the complexes of I with oligo-and poly(acrylic acid)s were also studied by ORD in aqueous solutions and by x-ray analysis in the crystalline state. The results showed that the β-structure is preferred over the α helical conformation. This might be attributable to the fact that the distance between the neighboring carboxylic groups along II is shorter than that between the adjacent amino group of I in the α-helical form but coincides with the distance in the β-structure. On the basis of the structural information obtained, the polymerization of acrylic acid and potassium p-vinylbenzene sulfonate in the presence of poly-L-lysine was examined in terms of the polymerization kinetics and the structure of resultant polymer complexes. It was found that the polymerization was accelerated in the presence of poly-L-lysine only when it has a β-structure in the beginning or in the final stages of polymerization.